STRIDE Analysis Patterns

Systematic threat identification using the STRIDE methodology.

When to Use This Skill

• Starting new threat modeling sessions
• Analyzing existing system architecture
• Reviewing security design decisions
• Creating threat documentation
• Training teams on threat identification
• Compliance and audit preparation

Core Concepts

1. STRIDE Categories

S - Spoofing       → Authentication threats
T - Tampering      → Integrity threats
R - Repudiation    → Non-repudiation threats
I - Information    → Confidentiality threats
    Disclosure
D - Denial of      → Availability threats
    Service
E - Elevation of   → Authorization threats
    Privilege

2. Threat Analysis Matrix

Templates

Template 1: STRIDE Threat Model Document

# Threat Model: [System Name]

## 1. System Overview

### 1.1 Description

[Brief description of the system and its purpose]

### 1.2 Data Flow Diagram

[User] --> [Web App] --> [API Gateway] --> [Backend Services] | v [Database]

### 1.3 Trust Boundaries
- **External Boundary**: Internet to DMZ
- **Internal Boundary**: DMZ to Internal Network
- **Data Boundary**: Application to Database

## 2. Assets

| Asset | Sensitivity | Description |
|-------|-------------|-------------|
| User Credentials | High | Authentication tokens, passwords |
| Personal Data | High | PII, financial information |
| Session Data | Medium | Active user sessions |
| Application Logs | Medium | System activity records |
| Configuration | High | System settings, secrets |

## 3. STRIDE Analysis

### 3.1 Spoofing Threats

| ID | Threat | Target | Impact | Likelihood |
|----|--------|--------|--------|------------|
| S1 | Session hijacking | User sessions | High | Medium |
| S2 | Token forgery | JWT tokens | High | Low |
| S3 | Credential stuffing | Login endpoint | High | High |

**Mitigations:**
- [ ] Implement MFA
- [ ] Use secure session management
- [ ] Implement account lockout policies

### 3.2 Tampering Threats

| ID | Threat | Target | Impact | Likelihood |
|----|--------|--------|--------|------------|
| T1 | SQL injection | Database queries | Critical | Medium |
| T2 | Parameter manipulation | API requests | High | High |
| T3 | File upload abuse | File storage | High | Medium |

**Mitigations:**
- [ ] Input validation on all endpoints
- [ ] Parameterized queries
- [ ] File type validation

### 3.3 Repudiation Threats

| ID | Threat | Target | Impact | Likelihood |
|----|--------|--------|--------|------------|
| R1 | Transaction denial | Financial ops | High | Medium |
| R2 | Access log tampering | Audit logs | Medium | Low |
| R3 | Action attribution | User actions | Medium | Medium |

**Mitigations:**
- [ ] Comprehensive audit logging
- [ ] Log integrity protection
- [ ] Digital signatures for critical actions

### 3.4 Information Disclosure Threats

| ID | Threat | Target | Impact | Likelihood |
|----|--------|--------|--------|------------|
| I1 | Data breach | User PII | Critical | Medium |
| I2 | Error message leakage | System info | Low | High |
| I3 | Insecure transmission | Network traffic | High | Medium |

**Mitigations:**
- [ ] Encryption at rest and in transit
- [ ] Sanitize error messages
- [ ] Implement TLS 1.3

### 3.5 Denial of Service Threats

| ID | Threat | Target | Impact | Likelihood |
|----|--------|--------|--------|------------|
| D1 | Resource exhaustion | API servers | High | High |
| D2 | Database overload | Database | Critical | Medium |
| D3 | Bandwidth saturation | Network | High | Medium |

**Mitigations:**
- [ ] Rate limiting
- [ ] Auto-scaling
- [ ] DDoS protection

### 3.6 Elevation of Privilege Threats

| ID | Threat | Target | Impact | Likelihood |
|----|--------|--------|--------|------------|
| E1 | IDOR vulnerabilities | User resources | High | High |
| E2 | Role manipulation | Admin access | Critical | Low |
| E3 | JWT claim tampering | Authorization | High | Medium |

**Mitigations:**
- [ ] Proper authorization checks
- [ ] Principle of least privilege
- [ ] Server-side role validation

## 4. Risk Assessment

### 4.1 Risk Matrix

          IMPACT
     Low  Med  High Crit
Low   1    2    3    4

L Med 2 4 6 8 I High 3 6 9 12 K Crit 4 8 12 16

### 4.2 Prioritized Risks

| Rank | Threat | Risk Score | Priority |
|------|--------|------------|----------|
| 1 | SQL Injection (T1) | 12 | Critical |
| 2 | IDOR (E1) | 9 | High |
| 3 | Credential Stuffing (S3) | 9 | High |
| 4 | Data Breach (I1) | 8 | High |

## 5. Recommendations

### Immediate Actions
1. Implement input validation framework
2. Add rate limiting to authentication endpoints
3. Enable comprehensive audit logging

### Short-term (30 days)
1. Deploy WAF with OWASP ruleset
2. Implement MFA for sensitive operations
3. Encrypt all PII at rest

### Long-term (90 days)
1. Security awareness training
2. Penetration testing
3. Bug bounty program

Template 2: STRIDE Analysis Code

from dataclasses import dataclass, field
from enum import Enum
from typing import List, Dict, Optional
import json

class StrideCategory(Enum):
    SPOOFING = "S"
    TAMPERING = "T"
    REPUDIATION = "R"
    INFORMATION_DISCLOSURE = "I"
    DENIAL_OF_SERVICE = "D"
    ELEVATION_OF_PRIVILEGE = "E"


class Impact(Enum):
    LOW = 1
    MEDIUM = 2
    HIGH = 3
    CRITICAL = 4


class Likelihood(Enum):
    LOW = 1
    MEDIUM = 2
    HIGH = 3
    CRITICAL = 4


@dataclass
class Threat:
    id: str
    category: StrideCategory
    title: str
    description: str
    target: str
    impact: Impact
    likelihood: Likelihood
    mitigations: List[str] = field(default_factory=list)
    status: str = "open"

    @property
    def risk_score(self) -> int:
        return self.impact.value * self.likelihood.value

    @property
    def risk_level(self) -> str:
        score = self.risk_score
        if score >= 12:
            return "Critical"
        elif score >= 6:
            return "High"
        elif score >= 3:
            return "Medium"
        return "Low"


@dataclass
class Asset:
    name: str
    sensitivity: str
    description: str
    data_classification: str


@dataclass
class TrustBoundary:
    name: str
    description: str
    from_zone: str
    to_zone: str


@dataclass
class ThreatModel:
    name: str
    version: str
    description: str
    assets: List[Asset] = field(default_factory=list)
    boundaries: List[TrustBoundary] = field(default_factory=list)
    threats: List[Threat] = field(default_factory=list)

    def add_threat(self, threat: Threat) -> None:
        self.threats.append(threat)

    def get_threats_by_category(self, category: StrideCategory) -> List[Threat]:
        return [t for t in self.threats if t.category == category]